There is known a library apparatus capable of storing plural information record media such as magnetic tapes in its housing and transferring those information record media to an information input-output device such as a magnetic tape drive by a robot to input and output information. A barcode for identification is put on an information record medium, and a barcode read device for reading the barcode is attached to the robot. The robot reads a barcode of an information record medium placed at an information record medium transfer in-and-out opening, transfers and stores the information record medium. As a barcode read device, an optical barcode read device that uses an imaging element such as CCD (Charge Coupled Device) is widely used.
In a housing of the library apparatus, there are provided some fans for radiating heat, which are driven at power-on. This driving of fans generates an air flow in the housing, and sometimes results in entering of a dust outside the device into the housing. There is also dust floating in the housing, produced by a friction between an information record medium and a storage shelf. When the dust attaches to a CCD lens of the barcode read device and makes the CCD lens dirty and dusty, a read error in which a barcode may not be read correctly may probably occur.
If this read error occurs, a maintenance person is notified of and a cleaning operation of the CCD lens is performed by the maintenance person. However, until the cleaning operation is finished, the operation of the library apparatus is suspended.
Conventionally, for example, in the field of magneto-optical disc driving device, there is disclosed a method of preventing a lens from becoming dirty and dusty (see Japanese Laid-open Patent Application No. 06-208726, for example). In the method, a dust-proof cover is disposed to prevent a light-pickup lens from becoming dirty and dusty, in such a manner that the dust-proof cover is in a shield position where the dust-proof cover covers the lens when a cartridge incorporating a disc is not loaded in the device, whereas when the cartridge is loaded in the device, the dust-proof cover is pushed by the disc cartridge and moved to a waiting position, and returns to the original shield position when the cartridge is unloaded from the device.
In the magneto-optical disc driving device of the above-described Japanese Laid-open Patent Application No. 06-208726, it is possible to prevent a lens from becoming dirty and dusty by this simple method that a position of the dust-proof cover is changed according to whether a cartridge is loaded or unloaded in and from the device. However, it is difficult to apply this method to the above-described library apparatus. That is, when an information record medium is transferred to the library apparatus, the robot is required to move to the medium transfer in-and-out opening where the information record medium is placed and to read a barcode of the information record medium. However, if the method of preventing a lens from becoming dirty and dusty by a dust proof cover as in the above-described Japanese Laid-open Patent Application No. 06-208726 is applied, firstly, the dust proof cover needs to be moved from a shield position to a waiting position to read the barcode, and after having read the barcode, the dust proof cover needs to be returned to the original shield position. However, since an operation to move the dust proof cover to the waiting position and operation to return the dust proof cover to the original shield position are irrelevant to a relative position change between the information record medium and the robot, it is impossible to prevent a lens from becoming dirty and dusty with such simple mechanism as in the above-described Japanese Laid-open Patent Application No. 06-208726.